In general, the cyclone dust collecting device is applied to a vacuum cleaner, for separating foreign matters, such as dust, from circulating air, to collect the dust.
The cyclone principle utilizes a difference of centrifugal forces for separating foreign matters, such as dust, from air circulating in a spiral.
Recently, the cyclone dust collecting device, collecting dust by using, the cyclone principle, is generally applied to the vacuum cleaner owing to advantages of the cyclone dust collecting device in that dust collecting performance is good and dust can be removed easily compared to a bag-type dust collecting device in which a dust bag is mounted in an air flow passage for collecting dust.
A related art dust collecting device for a vacuum cleaner will be described with, reference to FIG. 1.
The related art dust collecting device is provided with a primary cyclone dust colleting unit 10 for drawing contaminated air containing dust and collecting comparatively large sized particles of the dust therefrom, and a secondary cyclone dust collecting unit 20 on an outside of the primary cyclone dust colleting unit 10 for collecting comparatively small sized particles of the dust.
The primary cyclone dust collecting unit 10, a cylindrical container having a bottom in close contact with a bottom of the dust collecting device, has a suction pipe 11 in a side surface of an upper portion for introduction of contaminated air containing foreign matters in a tangential direction of an inside wall of the primary cyclone dust collecting unit, and a discharge opening 12 at a center of a top for discharging air cleaned primarily.
According to this, the primary cyclone dust collecting unit 10 has an upper space forming a primary cyclone 13 for separating foreign matters by centrifugal force, and a lower space forming a primary dust storage portion 14 for storing foreign matters separated by the centrifugal force.
In the meantime, the air from the discharge opening 12 is introduced to the secondary cyclone dust collecting unit 20, and discharged upward after passed through a dust separating step, again.
In more detail, the secondary cyclone dust collecting unit 20 includes a plurality of small sized secondary cyclones 21 arranged in a circumferential direction around the upper portion of the primary cyclone dust collecting unit 10, and a secondary dust storage portion 22 for storing dust separated at the secondary cyclone dust collecting unit 21.
The secondary dust storage portion 22 is under the secondary cyclones 21 around the primary dust storage portion. The primary dust storage portion 14 and the secondary dust storage portion 22 are separated by an outside wall of the primary cyclone dust collecting unit 10.
However, the related art dust collecting device has a problem in that a dust collecting performance of the primary cyclone dust collecting unit that collects a major portion of the dust is poor because the foreign matters, such as dust, is separated and collected only with single primary cyclone unit.
Moreover, since the suction pipe is asymmetric, which is extended from one side of the related art dust collecting device toward a center portion thereof, the related art dust collecting device has problems in that the suction pipe is long, air tightness between the cleaner body and the dust collecting device is poor, and a air flow resistance is high due to the bent air flow passage.
Because the primary cyclone and the primary dust storage portion are formed as one unit in the cylindrical primary cyclone dust collecting unit having the same upper and lower inside diameters, the dust flies up from the primary dust storage portion toward an upper side of the primary cyclone by the spiral circulation of air in the primary cyclone, thereby leading the dust collecting performance poor.
Furthermore, in the related art dust collecting device, because the secondary dust storage portion is around the primary dust storage portion, if a capacity of the primary dust storage portion is made greater, a width of the secondary dust storage portion becomes smaller, causing difficulty both in removal of foreign matters from a wall of he secondary dust storage portion, and checking an amount of dust accumulated in the primary dust storage portion due to the secondary dust storage portion that shades the primary dust storage portion.